If you want I have a gopro you can borrow to get a video should be able to hang it off the back of your bike....I hear you buddy but While this is going on I really can't be on the trail and on the phone and controlling my situation.
I tried explaining this to the owner as well who feels unless I had it on video tape he didn't believe it. If I'm in a situation where I am scared and I think I'm going to have to defend myself pulling a phone out to videotape is very difficult.
I'm not buying a go pro for the situation I would rather carry pepper spray or alert the authorities